Method and apparatus for detecting damage in armor structures

A computer-implemented method of determining health of a structure, comprising:

• in a system including a plurality of transducers affixed to the structure so as to define one or more paths between pairs of the transducers, transmitting a querying signal through the structure along one of the paths;
• detecting the querying signal at an end of the one of the paths so as to form a detected signal;
• repeating the transmitting and the detecting for each path of the one or more paths, so as to generate a plurality of detected signals;
• and
• determining whether a damage to the structure is present, the determining performed according to the plurality of detected signals;
• wherein the determining whether a damage to the structure is present further comprises:
• determining indices according to differences between energies of the detected signals and an energy of a predetermined baseline signal;
• determining a mean of the indices and a skewness of the indices;
• and
• comparing the mean of the indices to a first predetermined threshold, and the skewness of the indices to a second predetermined threshold.

A computer-implemented method of determining health of a structure, comprising:

• in a system including a plurality of transducers affixed to the structure so as to define one or more paths between pairs of the transducers, transmitting a first signal to a first transducer located at a first end of one of the paths;
• detecting a second signal at a second transducer located at a second end of the one of the paths, the second end opposite to the first end along the one of the paths;
• determining whether damage to the structure is present along the one of the paths, the determining performed according to a comparison of the second signal to a predetermined baseline signal;
• and
• repeating the transmitting and the detecting for each path of the one or more paths, so as to generate a plurality of second signals;
• wherein the determining whether damage to the structure is present further comprises:
• determining indices according to differences between energies of the second signals and an energy of a predetermined baseline signal;
• determining a mean of the indices and a skewness of the indices;
• and
• comparing the mean of the indices to a first predetermined threshold, and the skewness of the indices to a second predetermined threshold.

A computer-implemented method of determining probability of detection POD values for a structure having a plurality of transducers affixed thereto, the method comprising:

• in a system including a plurality of transducers affixed to the structureso as to define one or more paths along the structure between pairs of the transducers:
• A) determining a value k of a characteristic dimension for a possible damage;
• B) determining a number of locations N within a surface area defined by the plurality of transducers on the structure;
• C) determining a number nk of the determined locations at which the possible damage having the value k of the characteristic dimension intersects one or more of the paths;
• D) determining a probability of detection PODk =nk/N;
• and
• E) successively incrementing k, and repeating B) through D) for each successively incremented value of k.

A non-transitory computer-readable medium storing instructions for carrying out a method with a system including a structure and a plurality of transducers affixed to the structure so as to define one or more paths between pairs of the transducers, the method comprising:

• determining a probability of detection curve corresponding to probabilities that the plurality of transducers will detect differently sized damages to the structure,wherein the determining a probability of detection curve further comprises:
• A) determining a value k of a characteristic dimension for a possible damage;
• B) determining a number of locations N within a surface area defined by the plurality of transducers on the structure;
• C) determining a number nk of the determined locations at which the possible damage having the value k of the characteristic dimension intersects one or more of the paths;
• D) determining a probability of detection PODk=nk/N;
• E) successively incrementing k, and repeating B) through D) for each successively incremented value of k.

A non-transitory computer-readable medium storing instructions for carrying out a method with a system including a plurality of transducers affixed to astructure so as to define one or more paths between pairs of the transducers, the method comprising:

• transmitting a first signal to a first transducer located at a first end of one of the paths;
• detecting a second signal at a second transducer located at a second end of the one of the paths, the second end opposite to the first end along the one of the paths;
• determining whether damage to the structure is present along the one of the paths, the determining performed according to a comparison of the second signal to a predetermined baseline signal;
• and
• repeating the transmitting and the detecting for each path of the one or more paths, so as to generate a plurality of second signals;
• wherein the determining whether damage to the structure is present further comprises:
• determining indices according to differences between energies of the second signals and an energy of a predetermined baseline signal;
• determining a mean of the indices and a skewness of the indices;
• and
• comparing the mean of the indices to a first predetermined threshold, and the skewness of the indices to a second predetermined threshold.